1. 02 Nov, 2017 1 commit
    • Greg Kroah-Hartman's avatar
      License cleanup: add SPDX GPL-2.0 license identifier to files with no license · b2441318
      Greg Kroah-Hartman authored
      Many source files in the tree are missing licensing information, which
      makes it harder for compliance tools to determine the correct license.
      
      By default all files without license information are under the default
      license of the kernel, which is GPL version 2.
      
      Update the files which contain no license information with the 'GPL-2.0'
      SPDX license identifier.  The SPDX identifier is a legally binding
      shorthand, which can be used instead of the full boiler plate text.
      
      This patch is based on work done by Thomas Gleixner and Kate Stewart and
      Philippe Ombredanne.
      
      How this work was done:
      
      Patches were generated and checked against linux-4.14-rc6 for a subset of
      the use cases:
       - file had no licensing information it it.
       - file was a */uapi/* one with no licensing information in it,
       - file was a */uapi/* one with existing licensing information,
      
      Further patches will be generated in subsequent months to fix up cases
      where non-standard license headers were used, and references to license
      had to be inferred by heuristics based on keywords.
      
      The analysis to determine which SPDX License Identifier to be applied to
      a file was done in a spreadsheet of side by side results from of the
      output of two independent scanners (ScanCode & Windriver) producing SPDX
      tag:value files created by Philippe Ombredanne.  Philippe prepared the
      base worksheet, and did an initial spot review of a few 1000 files.
      
      The 4.13 kernel was the starting point of the analysis with 60,537 files
      assessed.  Kate Stewart did a file by file comparison of the scanner
      results in the spreadsheet to determine which SPDX license identifier(s)
      to be applied to the file. She confirmed any determination that was not
      immediately clear with lawyers working with the Linux Foundation.
      
      Criteria used to select files for SPDX license identifier tagging was:
       - Files considered eligible had to be source code files.
       - Make and config files were included as candidates if they contained >5
         lines of source
       - File already had some variant of a license header in it (even if <5
         lines).
      
      All documentation files were explicitly excluded.
      
      The following heuristics were used to determine which SPDX license
      identifiers to apply.
      
       - when both scanners couldn't find any license traces, file was
         considered to have no license information in it, and the top level
         COPYING file license applied.
      
         For non */uapi/* files that summary was:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|-------
         GPL-2.0                                              11139
      
         and resulted in the first patch in this series.
      
         If that file was a */uapi/* path one, it was "GPL-2.0 WITH
         Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|-------
         GPL-2.0 WITH Linux-syscall-note                        930
      
         and resulted in the second patch in this series.
      
       - if a file had some form of licensing information in it, and was one
         of the */uapi/* ones, it was denoted with the Linux-syscall-note if
         any GPL family license was found in the file or had no licensing in
         it (per prior point).  Results summary:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|------
         GPL-2.0 WITH Linux-syscall-note                       270
         GPL-2.0+ WITH Linux-syscall-note                      169
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
         LGPL-2.1+ WITH Linux-syscall-note                      15
         GPL-1.0+ WITH Linux-syscall-note                       14
         ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
         LGPL-2.0+ WITH Linux-syscall-note                       4
         LGPL-2.1 WITH Linux-syscall-note                        3
         ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
         ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1
      
         and that resulted in the third patch in this series.
      
       - when the two scanners agreed on the detected license(s), that became
         the concluded license(s).
      
       - when there was disagreement between the two scanners (one detected a
         license but the other didn't, or they both detected different
         licenses) a manual inspection of the file occurred.
      
       - In most cases a manual inspection of the information in the file
         resulted in a clear resolution of the license that should apply (and
         which scanner probably needed to revisit its heuristics).
      
       - When it was not immediately clear, the license identifier was
         confirmed with lawyers working with the Linux Foundation.
      
       - If there was any question as to the appropriate license identifier,
         the file was flagged for further research and to be revisited later
         in time.
      
      In total, over 70 hours of logged manual review was done on the
      spreadsheet to determine the SPDX license identifiers to apply to the
      source files by Kate, Philippe, Thomas and, in some cases, confirmation
      by lawyers working with the Linux Foundation.
      
      Kate also obtained a third independent scan of the 4.13 code base from
      FOSSology, and compared selected files where the other two scanners
      disagreed against that SPDX file, to see if there was new insights.  The
      Windriver scanner is based on an older version of FOSSology in part, so
      they are related.
      
      Thomas did random spot checks in about 500 files from the spreadsheets
      for the uapi headers and agreed with SPDX license identifier in the
      files he inspected. For the non-uapi files Thomas did random spot checks
      in about 15000 files.
      
      In initial set of patches against 4.14-rc6, 3 files were found to have
      copy/paste license identifier errors, and have been fixed to reflect the
      correct identifier.
      
      Additionally Philippe spent 10 hours this week doing a detailed manual
      inspection and review of the 12,461 patched files from the initial patch
      version early this week with:
       - a full scancode scan run, collecting the matched texts, detected
         license ids and scores
       - reviewing anything where there was a license detected (about 500+
         files) to ensure that the applied SPDX license was correct
       - reviewing anything where there was no detection but the patch license
         was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
         SPDX license was correct
      
      This produced a worksheet with 20 files needing minor correction.  This
      worksheet was then exported into 3 different .csv files for the
      different types of files to be modified.
      
      These .csv files were then reviewed by Greg.  Thomas wrote a script to
      parse the csv files and add the proper SPDX tag to the file, in the
      format that the file expected.  This script was further refined by Greg
      based on the output to detect more types of files automatically and to
      distinguish between header and source .c files (which need different
      comment types.)  Finally Greg ran the script using the .csv files to
      generate the patches.
      Reviewed-by: default avatarKate Stewart <kstewart@linuxfoundation.org>
      Reviewed-by: default avatarPhilippe Ombredanne <pombredanne@nexb.com>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b2441318
  2. 09 Oct, 2017 1 commit
  3. 17 Aug, 2017 1 commit
    • Kees Cook's avatar
      locking/refcounts, x86/asm: Implement fast refcount overflow protection · 7a46ec0e
      Kees Cook authored
      This implements refcount_t overflow protection on x86 without a noticeable
      performance impact, though without the fuller checking of REFCOUNT_FULL.
      
      This is done by duplicating the existing atomic_t refcount implementation
      but with normally a single instruction added to detect if the refcount
      has gone negative (e.g. wrapped past INT_MAX or below zero). When detected,
      the handler saturates the refcount_t to INT_MIN / 2. With this overflow
      protection, the erroneous reference release that would follow a wrap back
      to zero is blocked from happening, avoiding the class of refcount-overflow
      use-after-free vulnerabilities entirely.
      
      Only the overflow case of refcounting can be perfectly protected, since
      it can be detected and stopped before the reference is freed and left to
      be abused by an attacker. There isn't a way to block early decrements,
      and while REFCOUNT_FULL stops increment-from-zero cases (which would
      be the state _after_ an early decrement and stops potential double-free
      conditions), this fast implementation does not, since it would require
      the more expensive cmpxchg loops. Since the overflow case is much more
      common (e.g. missing a "put" during an error path), this protection
      provides real-world protection. For example, the two public refcount
      overflow use-after-free exploits published in 2016 would have been
      rendered unexploitable:
      
        http://perception-point.io/2016/01/14/analysis-and-exploitation-of-a-linux-kernel-vulnerability-cve-2016-0728/
      
        http://cyseclabs.com/page?n=02012016
      
      This implementation does, however, notice an unchecked decrement to zero
      (i.e. caller used refcount_dec() instead of refcount_dec_and_test() and it
      resulted in a zero). Decrements under zero are noticed (since they will
      have resulted in a negative value), though this only indicates that a
      use-after-free may have already happened. Such notifications are likely
      avoidable by an attacker that has already exploited a use-after-free
      vulnerability, but it's better to have them reported than allow such
      conditions to remain universally silent.
      
      On first overflow detection, the refcount value is reset to INT_MIN / 2
      (which serves as a saturation value) and a report and stack trace are
      produced. When operations detect only negative value results (such as
      changing an already saturated value), saturation still happens but no
      notification is performed (since the value was already saturated).
      
      On the matter of races, since the entire range beyond INT_MAX but before
      0 is negative, every operation at INT_MIN / 2 will trap, leaving no
      overflow-only race condition.
      
      As for performance, this implementation adds a single "js" instruction
      to the regular execution flow of a copy of the standard atomic_t refcount
      operations. (The non-"and_test" refcount_dec() function, which is uncommon
      in regular refcount design patterns, has an additional "jz" instruction
      to detect reaching exactly zero.) Since this is a forward jump, it is by
      default the non-predicted path, which will be reinforced by dynamic branch
      prediction. The result is this protection having virtually no measurable
      change in performance over standard atomic_t operations. The error path,
      located in .text.unlikely, saves the refcount location and then uses UD0
      to fire a refcount exception handler, which resets the refcount, handles
      reporting, and returns to regular execution. This keeps the changes to
      .text size minimal, avoiding return jumps and open-coded calls to the
      error reporting routine.
      
      Example assembly comparison:
      
      refcount_inc() before:
      
        .text:
        ffffffff81546149:       f0 ff 45 f4             lock incl -0xc(%rbp)
      
      refcount_inc() after:
      
        .text:
        ffffffff81546149:       f0 ff 45 f4             lock incl -0xc(%rbp)
        ffffffff8154614d:       0f 88 80 d5 17 00       js     ffffffff816c36d3
        ...
        .text.unlikely:
        ffffffff816c36d3:       48 8d 4d f4             lea    -0xc(%rbp),%rcx
        ffffffff816c36d7:       0f ff                   (bad)
      
      These are the cycle counts comparing a loop of refcount_inc() from 1
      to INT_MAX and back down to 0 (via refcount_dec_and_test()), between
      unprotected refcount_t (atomic_t), fully protected REFCOUNT_FULL
      (refcount_t-full), and this overflow-protected refcount (refcount_t-fast):
      
        2147483646 refcount_inc()s and 2147483647 refcount_dec_and_test()s:
      		    cycles		protections
        atomic_t           82249267387	none
        refcount_t-fast    82211446892	overflow, untested dec-to-zero
        refcount_t-full   144814735193	overflow, untested dec-to-zero, inc-from-zero
      
      This code is a modified version of the x86 PAX_REFCOUNT atomic_t
      overflow defense from the last public patch of PaX/grsecurity, based
      on my understanding of the code. Changes or omissions from the original
      code are mine and don't reflect the original grsecurity/PaX code. Thanks
      to PaX Team for various suggestions for improvement for repurposing this
      code to be a refcount-only protection.
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
      Cc: Alexey Dobriyan <adobriyan@gmail.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: David S. Miller <davem@davemloft.net>
      Cc: Davidlohr Bueso <dave@stgolabs.net>
      Cc: Elena Reshetova <elena.reshetova@intel.com>
      Cc: Eric Biggers <ebiggers3@gmail.com>
      Cc: Eric W. Biederman <ebiederm@xmission.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      Cc: Hans Liljestrand <ishkamiel@gmail.com>
      Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
      Cc: Jann Horn <jannh@google.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Serge E. Hallyn <serge@hallyn.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: arozansk@redhat.com
      Cc: axboe@kernel.dk
      Cc: kernel-hardening@lists.openwall.com
      Cc: linux-arch <linux-arch@vger.kernel.org>
      Link: http://lkml.kernel.org/r/20170815161924.GA133115@beastSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      7a46ec0e
  4. 07 Aug, 2017 1 commit
    • Ard Biesheuvel's avatar
      gcc-plugins: structleak: add option to init all vars used as byref args · f7dd2507
      Ard Biesheuvel authored
      In the Linux kernel, struct type variables are rarely passed by-value,
      and so functions that initialize such variables typically take an input
      reference to the variable rather than returning a value that can
      subsequently be used in an assignment.
      
      If the initalization function is not part of the same compilation unit,
      the lack of an assignment operation defeats any analysis the compiler
      can perform as to whether the variable may be used before having been
      initialized. This means we may end up passing on such variables
      uninitialized, resulting in potential information leaks.
      
      So extend the existing structleak GCC plugin so it will [optionally]
      apply to all struct type variables that have their address taken at any
      point, rather than only to variables of struct types that have a __user
      annotation.
      Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      f7dd2507
  5. 02 Aug, 2017 1 commit
  6. 12 Jul, 2017 2 commits
    • Daniel Micay's avatar
      include/linux/string.h: add the option of fortified string.h functions · 6974f0c4
      Daniel Micay authored
      This adds support for compiling with a rough equivalent to the glibc
      _FORTIFY_SOURCE=1 feature, providing compile-time and runtime buffer
      overflow checks for string.h functions when the compiler determines the
      size of the source or destination buffer at compile-time.  Unlike glibc,
      it covers buffer reads in addition to writes.
      
      GNU C __builtin_*_chk intrinsics are avoided because they would force a
      much more complex implementation.  They aren't designed to detect read
      overflows and offer no real benefit when using an implementation based
      on inline checks.  Inline checks don't add up to much code size and
      allow full use of the regular string intrinsics while avoiding the need
      for a bunch of _chk functions and per-arch assembly to avoid wrapper
      overhead.
      
      This detects various overflows at compile-time in various drivers and
      some non-x86 core kernel code.  There will likely be issues caught in
      regular use at runtime too.
      
      Future improvements left out of initial implementation for simplicity,
      as it's all quite optional and can be done incrementally:
      
      * Some of the fortified string functions (strncpy, strcat), don't yet
        place a limit on reads from the source based on __builtin_object_size of
        the source buffer.
      
      * Extending coverage to more string functions like strlcat.
      
      * It should be possible to optionally use __builtin_object_size(x, 1) for
        some functions (C strings) to detect intra-object overflows (like
        glibc's _FORTIFY_SOURCE=2), but for now this takes the conservative
        approach to avoid likely compatibility issues.
      
      * The compile-time checks should be made available via a separate config
        option which can be enabled by default (or always enabled) once enough
        time has passed to get the issues it catches fixed.
      
      Kees said:
       "This is great to have. While it was out-of-tree code, it would have
        blocked at least CVE-2016-3858 from being exploitable (improper size
        argument to strlcpy()). I've sent a number of fixes for
        out-of-bounds-reads that this detected upstream already"
      
      [arnd@arndb.de: x86: fix fortified memcpy]
        Link: http://lkml.kernel.org/r/20170627150047.660360-1-arnd@arndb.de
      [keescook@chromium.org: avoid panic() in favor of BUG()]
        Link: http://lkml.kernel.org/r/20170626235122.GA25261@beast
      [keescook@chromium.org: move from -mm, add ARCH_HAS_FORTIFY_SOURCE, tweak Kconfig help]
      Link: http://lkml.kernel.org/r/20170526095404.20439-1-danielmicay@gmail.com
      Link: http://lkml.kernel.org/r/1497903987-21002-8-git-send-email-keescook@chromium.orgSigned-off-by: default avatarDaniel Micay <danielmicay@gmail.com>
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      Acked-by: default avatarKees Cook <keescook@chromium.org>
      Cc: Mark Rutland <mark.rutland@arm.com>
      Cc: Daniel Axtens <dja@axtens.net>
      Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
      Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
      Cc: Chris Metcalf <cmetcalf@ezchip.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6974f0c4
    • Nicholas Piggin's avatar
      kernel/watchdog: split up config options · 05a4a952
      Nicholas Piggin authored
      Split SOFTLOCKUP_DETECTOR from LOCKUP_DETECTOR, and split
      HARDLOCKUP_DETECTOR_PERF from HARDLOCKUP_DETECTOR.
      
      LOCKUP_DETECTOR implies the general boot, sysctl, and programming
      interfaces for the lockup detectors.
      
      An architecture that wants to use a hard lockup detector must define
      HAVE_HARDLOCKUP_DETECTOR_PERF or HAVE_HARDLOCKUP_DETECTOR_ARCH.
      
      Alternatively an arch can define HAVE_NMI_WATCHDOG, which provides the
      minimum arch_touch_nmi_watchdog, and it otherwise does its own thing and
      does not implement the LOCKUP_DETECTOR interfaces.
      
      sparc is unusual in that it has started to implement some of the
      interfaces, but not fully yet.  It should probably be converted to a full
      HAVE_HARDLOCKUP_DETECTOR_ARCH.
      
      [npiggin@gmail.com: fix]
        Link: http://lkml.kernel.org/r/20170617223522.66c0ad88@roar.ozlabs.ibm.com
      Link: http://lkml.kernel.org/r/20170616065715.18390-4-npiggin@gmail.comSigned-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
      Reviewed-by: default avatarDon Zickus <dzickus@redhat.com>
      Reviewed-by: default avatarBabu Moger <babu.moger@oracle.com>
      Tested-by: Babu Moger <babu.moger@oracle.com>	[sparc]
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Michael Ellerman <mpe@ellerman.id.au>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      05a4a952
  7. 30 Jun, 2017 1 commit
  8. 28 Jun, 2017 1 commit
    • Kees Cook's avatar
      locking/refcount: Create unchecked atomic_t implementation · fd25d19f
      Kees Cook authored
      Many subsystems will not use refcount_t unless there is a way to build the
      kernel so that there is no regression in speed compared to atomic_t. This
      adds CONFIG_REFCOUNT_FULL to enable the full refcount_t implementation
      which has the validation but is slightly slower. When not enabled,
      refcount_t uses the basic unchecked atomic_t routines, which results in
      no code changes compared to just using atomic_t directly.
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      Cc: Alexey Dobriyan <adobriyan@gmail.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: David S. Miller <davem@davemloft.net>
      Cc: David Windsor <dwindsor@gmail.com>
      Cc: Davidlohr Bueso <dave@stgolabs.net>
      Cc: Elena Reshetova <elena.reshetova@intel.com>
      Cc: Eric Biggers <ebiggers3@gmail.com>
      Cc: Eric W. Biederman <ebiederm@xmission.com>
      Cc: Hans Liljestrand <ishkamiel@gmail.com>
      Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
      Cc: Jann Horn <jannh@google.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Serge E. Hallyn <serge@hallyn.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: arozansk@redhat.com
      Cc: axboe@kernel.dk
      Cc: linux-arch <linux-arch@vger.kernel.org>
      Link: http://lkml.kernel.org/r/20170621200026.GA115679@beastSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      fd25d19f
  9. 22 Jun, 2017 1 commit
    • Kees Cook's avatar
      gcc-plugins: Add the randstruct plugin · 313dd1b6
      Kees Cook authored
      This randstruct plugin is modified from Brad Spengler/PaX Team's code
      in the last public patch of grsecurity/PaX based on my understanding
      of the code. Changes or omissions from the original code are mine and
      don't reflect the original grsecurity/PaX code.
      
      The randstruct GCC plugin randomizes the layout of selected structures
      at compile time, as a probabilistic defense against attacks that need to
      know the layout of structures within the kernel. This is most useful for
      "in-house" kernel builds where neither the randomization seed nor other
      build artifacts are made available to an attacker. While less useful for
      distribution kernels (where the randomization seed must be exposed for
      third party kernel module builds), it still has some value there since now
      all kernel builds would need to be tracked by an attacker.
      
      In more performance sensitive scenarios, GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
      can be selected to make a best effort to restrict randomization to
      cacheline-sized groups of elements, and will not randomize bitfields. This
      comes at the cost of reduced randomization.
      
      Two annotations are defined,__randomize_layout and __no_randomize_layout,
      which respectively tell the plugin to either randomize or not to
      randomize instances of the struct in question. Follow-on patches enable
      the auto-detection logic for selecting structures for randomization
      that contain only function pointers. It is disabled here to assist with
      bisection.
      
      Since any randomized structs must be initialized using designated
      initializers, __randomize_layout includes the __designated_init annotation
      even when the plugin is disabled so that all builds will require
      the needed initialization. (With the plugin enabled, annotations for
      automatically chosen structures are marked as well.)
      
      The main differences between this implemenation and grsecurity are:
      - disable automatic struct selection (to be enabled in follow-up patch)
      - add designated_init attribute at runtime and for manual marking
      - clarify debugging output to differentiate bad cast warnings
      - add whitelisting infrastructure
      - support gcc 7's DECL_ALIGN and DECL_MODE changes (Laura Abbott)
      - raise minimum required GCC version to 4.7
      
      Earlier versions of this patch series were ported by Michael Leibowitz.
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      313dd1b6
  10. 19 Jun, 2017 1 commit
  11. 09 May, 2017 1 commit
    • Hari Bathini's avatar
      crash: move crashkernel parsing and vmcore related code under CONFIG_CRASH_CORE · 692f66f2
      Hari Bathini authored
      Patch series "kexec/fadump: remove dependency with CONFIG_KEXEC and
      reuse crashkernel parameter for fadump", v4.
      
      Traditionally, kdump is used to save vmcore in case of a crash.  Some
      architectures like powerpc can save vmcore using architecture specific
      support instead of kexec/kdump mechanism.  Such architecture specific
      support also needs to reserve memory, to be used by dump capture kernel.
      crashkernel parameter can be a reused, for memory reservation, by such
      architecture specific infrastructure.
      
      This patchset removes dependency with CONFIG_KEXEC for crashkernel
      parameter and vmcoreinfo related code as it can be reused without kexec
      support.  Also, crashkernel parameter is reused instead of
      fadump_reserve_mem to reserve memory for fadump.
      
      The first patch moves crashkernel parameter parsing and vmcoreinfo
      related code under CONFIG_CRASH_CORE instead of CONFIG_KEXEC_CORE.  The
      second patch reuses the definitions of append_elf_note() & final_note()
      functions under CONFIG_CRASH_CORE in IA64 arch code.  The third patch
      removes dependency on CONFIG_KEXEC for firmware-assisted dump (fadump)
      in powerpc.  The next patch reuses crashkernel parameter for reserving
      memory for fadump, instead of the fadump_reserve_mem parameter.  This
      has the advantage of using all syntaxes crashkernel parameter supports,
      for fadump as well.  The last patch updates fadump kernel documentation
      about use of crashkernel parameter.
      
      This patch (of 5):
      
      Traditionally, kdump is used to save vmcore in case of a crash.  Some
      architectures like powerpc can save vmcore using architecture specific
      support instead of kexec/kdump mechanism.  Such architecture specific
      support also needs to reserve memory, to be used by dump capture kernel.
      crashkernel parameter can be a reused, for memory reservation, by such
      architecture specific infrastructure.
      
      But currently, code related to vmcoreinfo and parsing of crashkernel
      parameter is built under CONFIG_KEXEC_CORE.  This patch introduces
      CONFIG_CRASH_CORE and moves the above mentioned code under this config,
      allowing code reuse without dependency on CONFIG_KEXEC.  There is no
      functional change with this patch.
      
      Link: http://lkml.kernel.org/r/149035338104.6881.4550894432615189948.stgit@hbathini.in.ibm.comSigned-off-by: default avatarHari Bathini <hbathini@linux.vnet.ibm.com>
      Acked-by: default avatarDave Young <dyoung@redhat.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Cc: Michael Ellerman <mpe@ellerman.id.au>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      692f66f2
  12. 26 Apr, 2017 1 commit
  13. 18 Apr, 2017 1 commit
  14. 28 Mar, 2017 1 commit
  15. 13 Mar, 2017 1 commit
    • Dmitry Safonov's avatar
      x86/mm: Introduce mmap_compat_base() for 32-bit mmap() · 1b028f78
      Dmitry Safonov authored
      mmap() uses a base address, from which it starts to look for a free space
      for allocation.
      
      The base address is stored in mm->mmap_base, which is calculated during
      exec(). The address depends on task's size, set rlimit for stack, ASLR
      randomization. The base depends on the task size and the number of random
      bits which are different for 64-bit and 32bit applications.
      
      Due to the fact, that the base address is fixed, its mmap() from a compat
      (32bit) syscall issued by a 64bit task will return a address which is based
      on the 64bit base address and does not fit into the 32bit address space
      (4GB). The returned pointer is truncated to 32bit, which results in an
      invalid address.
      
      To solve store a seperate compat address base plus a compat legacy address
      base in mm_struct. These bases are calculated at exec() time and can be
      used later to address the 32bit compat mmap() issued by 64 bit
      applications.
      
      As a consequence of this change 32-bit applications issuing a 64-bit
      syscall (after doing a long jump) will get a 64-bit mapping now. Before
      this change 32-bit applications always got a 32bit mapping.
      
      [ tglx: Massaged changelog and added a comment ]
      Signed-off-by: default avatarDmitry Safonov <dsafonov@virtuozzo.com>
      Cc: 0x7f454c46@gmail.com
      Cc: linux-mm@kvack.org
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Cyrill Gorcunov <gorcunov@openvz.org>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
      Link: http://lkml.kernel.org/r/20170306141721.9188-4-dsafonov@virtuozzo.comSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      1b028f78
  16. 08 Mar, 2017 1 commit
    • Josh Poimboeuf's avatar
      stacktrace/x86: add function for detecting reliable stack traces · af085d90
      Josh Poimboeuf authored
      For live patching and possibly other use cases, a stack trace is only
      useful if it can be assured that it's completely reliable.  Add a new
      save_stack_trace_tsk_reliable() function to achieve that.
      
      Note that if the target task isn't the current task, and the target task
      is allowed to run, then it could be writing the stack while the unwinder
      is reading it, resulting in possible corruption.  So the caller of
      save_stack_trace_tsk_reliable() must ensure that the task is either
      'current' or inactive.
      
      save_stack_trace_tsk_reliable() relies on the x86 unwinder's detection
      of pt_regs on the stack.  If the pt_regs are not user-mode registers
      from a syscall, then they indicate an in-kernel interrupt or exception
      (e.g. preemption or a page fault), in which case the stack is considered
      unreliable due to the nature of frame pointers.
      
      It also relies on the x86 unwinder's detection of other issues, such as:
      
      - corrupted stack data
      - stack grows the wrong way
      - stack walk doesn't reach the bottom
      - user didn't provide a large enough entries array
      
      Such issues are reported by checking unwind_error() and !unwind_done().
      
      Also add CONFIG_HAVE_RELIABLE_STACKTRACE so arch-independent code can
      determine at build time whether the function is implemented.
      Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
      Reviewed-by: default avatarMiroslav Benes <mbenes@suse.cz>
      Acked-by: Ingo Molnar <mingo@kernel.org>	# for the x86 changes
      Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
      af085d90
  17. 28 Feb, 2017 1 commit
  18. 25 Feb, 2017 1 commit
  19. 21 Feb, 2017 1 commit
    • Daniel Borkmann's avatar
      arch: add ARCH_HAS_SET_MEMORY config · d2852a22
      Daniel Borkmann authored
      Currently, there's no good way to test for the presence of
      set_memory_ro/rw/x/nx() helpers implemented by archs such as
      x86, arm, arm64 and s390.
      
      There's DEBUG_SET_MODULE_RONX and DEBUG_RODATA, however both
      don't really reflect that: set_memory_*() are also available
      even when DEBUG_SET_MODULE_RONX is turned off, and DEBUG_RODATA
      is set by parisc, but doesn't implement above functions. Thus,
      add ARCH_HAS_SET_MEMORY that is selected by mentioned archs,
      where generic code can test against this.
      
      This also allows later on to move DEBUG_SET_MODULE_RONX out of
      the arch specific Kconfig to define it only once depending on
      ARCH_HAS_SET_MEMORY.
      Suggested-by: default avatarLaura Abbott <labbott@redhat.com>
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      d2852a22
  20. 07 Feb, 2017 2 commits
  21. 18 Jan, 2017 2 commits
  22. 20 Dec, 2016 1 commit
    • Thiago Jung Bauermann's avatar
      powerpc: ima: get the kexec buffer passed by the previous kernel · 467d2782
      Thiago Jung Bauermann authored
      Patch series "ima: carry the measurement list across kexec", v8.
      
      The TPM PCRs are only reset on a hard reboot.  In order to validate a
      TPM's quote after a soft reboot (eg.  kexec -e), the IMA measurement
      list of the running kernel must be saved and then restored on the
      subsequent boot, possibly of a different architecture.
      
      The existing securityfs binary_runtime_measurements file conveniently
      provides a serialized format of the IMA measurement list.  This patch
      set serializes the measurement list in this format and restores it.
      
      Up to now, the binary_runtime_measurements was defined as architecture
      native format.  The assumption being that userspace could and would
      handle any architecture conversions.  With the ability of carrying the
      measurement list across kexec, possibly from one architecture to a
      different one, the per boot architecture information is lost and with it
      the ability of recalculating the template digest hash.  To resolve this
      problem, without breaking the existing ABI, this patch set introduces
      the boot command line option "ima_canonical_fmt", which is arbitrarily
      defined as little endian.
      
      The need for this boot command line option will be limited to the
      existing version 1 format of the binary_runtime_measurements.
      Subsequent formats will be defined as canonical format (eg.  TPM 2.0
      support for larger digests).
      
      A simplified method of Thiago Bauermann's "kexec buffer handover" patch
      series for carrying the IMA measurement list across kexec is included in
      this patch set.  The simplified method requires all file measurements be
      taken prior to executing the kexec load, as subsequent measurements will
      not be carried across the kexec and restored.
      
      This patch (of 10):
      
      The IMA kexec buffer allows the currently running kernel to pass the
      measurement list via a kexec segment to the kernel that will be kexec'd.
      The second kernel can check whether the previous kernel sent the buffer
      and retrieve it.
      
      This is the architecture-specific part which enables IMA to receive the
      measurement list passed by the previous kernel.  It will be used in the
      next patch.
      
      The change in machine_kexec_64.c is to factor out the logic of removing
      an FDT memory reservation so that it can be used by remove_ima_buffer.
      
      Link: http://lkml.kernel.org/r/1480554346-29071-2-git-send-email-zohar@linux.vnet.ibm.comSigned-off-by: default avatarThiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
      Signed-off-by: default avatarMimi Zohar <zohar@linux.vnet.ibm.com>
      Acked-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
      Cc: Andreas Steffen <andreas.steffen@strongswan.org>
      Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
      Cc: Josh Sklar <sklar@linux.vnet.ibm.com>
      Cc: Dave Young <dyoung@redhat.com>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Cc: Baoquan He <bhe@redhat.com>
      Cc: Michael Ellerman <mpe@ellerman.id.au>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Stewart Smith <stewart@linux.vnet.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      467d2782
  23. 12 Dec, 2016 1 commit
  24. 15 Nov, 2016 1 commit
  25. 09 Nov, 2016 1 commit
    • Kees Cook's avatar
      gcc-plugins: Adjust Kconfig to avoid cyc_complexity · 215e2aa6
      Kees Cook authored
      In preparation for removing "depends on !COMPILE_TEST" from GCC_PLUGINS,
      the GCC_PLUGIN_CYC_COMPLEXITY plugin needs to gain the restriction,
      since it is mainly an example, and produces (intended) voluminous stderr
      reporting, which is generally undesirable for allyesconfig-style build
      tests. This additionally puts the plugin behind EXPERT and improves the
      help text.
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      215e2aa6
  26. 10 Oct, 2016 1 commit
    • Emese Revfy's avatar
      gcc-plugins: Add latent_entropy plugin · 38addce8
      Emese Revfy authored
      This adds a new gcc plugin named "latent_entropy". It is designed to
      extract as much possible uncertainty from a running system at boot time as
      possible, hoping to capitalize on any possible variation in CPU operation
      (due to runtime data differences, hardware differences, SMP ordering,
      thermal timing variation, cache behavior, etc).
      
      At the very least, this plugin is a much more comprehensive example for
      how to manipulate kernel code using the gcc plugin internals.
      
      The need for very-early boot entropy tends to be very architecture or
      system design specific, so this plugin is more suited for those sorts
      of special cases. The existing kernel RNG already attempts to extract
      entropy from reliable runtime variation, but this plugin takes the idea to
      a logical extreme by permuting a global variable based on any variation
      in code execution (e.g. a different value (and permutation function)
      is used to permute the global based on loop count, case statement,
      if/then/else branching, etc).
      
      To do this, the plugin starts by inserting a local variable in every
      marked function. The plugin then adds logic so that the value of this
      variable is modified by randomly chosen operations (add, xor and rol) and
      random values (gcc generates separate static values for each location at
      compile time and also injects the stack pointer at runtime). The resulting
      value depends on the control flow path (e.g., loops and branches taken).
      
      Before the function returns, the plugin mixes this local variable into
      the latent_entropy global variable. The value of this global variable
      is added to the kernel entropy pool in do_one_initcall() and _do_fork(),
      though it does not credit any bytes of entropy to the pool; the contents
      of the global are just used to mix the pool.
      
      Additionally, the plugin can pre-initialize arrays with build-time
      random contents, so that two different kernel builds running on identical
      hardware will not have the same starting values.
      Signed-off-by: default avatarEmese Revfy <re.emese@gmail.com>
      [kees: expanded commit message and code comments]
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      38addce8
  27. 22 Sep, 2016 1 commit
  28. 09 Sep, 2016 2 commits
    • Nicholas Piggin's avatar
      kbuild: allow archs to select link dead code/data elimination · b67067f1
      Nicholas Piggin authored
      Introduce LD_DEAD_CODE_DATA_ELIMINATION option for architectures to
      select to build with -ffunction-sections, -fdata-sections, and link
      with --gc-sections. It requires some work (documented) to ensure all
      unreferenced entrypoints are live, and requires toolchain and build
      verification, so it is made a per-arch option for now.
      
      On a random powerpc64le build, this yelds a significant size saving,
      it boots and runs fine, but there is a lot I haven't tested as yet, so
      these savings may be reduced if there are bugs in the link.
      
          text      data        bss        dec   filename
      11169741   1180744    1923176	14273661   vmlinux
      10445269   1004127    1919707	13369103   vmlinux.dce
      
      ~700K text, ~170K data, 6% removed from kernel image size.
      Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
      Signed-off-by: default avatarMichal Marek <mmarek@suse.com>
      b67067f1
    • Stephen Rothwell's avatar
      kbuild: allow architectures to use thin archives instead of ld -r · a5967db9
      Stephen Rothwell authored
      ld -r is an incremental link used to create built-in.o files in build
      subdirectories. It produces relocatable object files containing all
      its input files, and these are are then pulled together and relocated
      in the final link. Aside from the bloat, this constrains the final
      link relocations, which has bitten large powerpc builds with
      unresolvable relocations in the final link.
      
      Alan Modra has recommended the kernel use thin archives for linking.
      This is an alternative and means that the linker has more information
      available to it when it links the kernel.
      
      This patch enables a config option architectures can select, which
      causes all built-in.o files to be built as thin archives. built-in.o
      files in subdirectories do not get symbol table or index attached,
      which improves speed and size. The final link pass creates a
      built-in.o archive in the root output directory which includes the
      symbol table and index. The linker then uses takes this file to link.
      
      The --whole-archive linker option is required, because the linker now
      has visibility to every individual object file, and it will otherwise
      just completely avoid including those without external references
      (consider a file with EXPORT_SYMBOL or initcall or hardware exceptions
      as its only entry points). The traditional built works "by luck" as
      built-in.o files are large enough that they're going to get external
      references. However this optimisation is unpredictable for the kernel
      (due to above external references), ineffective at culling unused, and
      costly because the .o files have to be searched for references.
      Superior alternatives for link-time culling should be used instead.
      
      Build characteristics for inclink vs thinarc, on a small powerpc64le
      pseries VM with a modest .config:
      
                                        inclink       thinarc
      sizes
      vmlinux                        15 618 680    15 625 028
      sum of all built-in.o          56 091 808     1 054 334
      sum excluding root built-in.o                   151 430
      
      find -name built-in.o | xargs rm ; time make vmlinux
      real                              22.772s       21.143s
      user                              13.280s       13.430s
      sys                                4.310s        2.750s
      
      - Final kernel pulled in only about 6K more, which shows how
        ineffective the object file culling is.
      - Build performance looks improved due to less pagecache activity.
        On IO constrained systems it could be a bigger win.
      - Build size saving is significant.
      
      Side note, the toochain understands archives, so there's some tricks,
      $ ar t built-in.o          # list all files you linked with
      $ size built-in.o          # and their sizes
      $ objdump -d built-in.o    # disassembly (unrelocated) with filenames
      
      Implementation by sfr, minor tweaks by npiggin.
      Signed-off-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
      Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
      Signed-off-by: default avatarMichal Marek <mmarek@suse.com>
      a5967db9
  29. 07 Sep, 2016 1 commit
  30. 24 Aug, 2016 1 commit
  31. 09 Aug, 2016 1 commit
  32. 26 Jul, 2016 2 commits
  33. 24 Jun, 2016 1 commit
    • Linus Torvalds's avatar
      Clarify naming of thread info/stack allocators · b235beea
      Linus Torvalds authored
      We've had the thread info allocated together with the thread stack for
      most architectures for a long time (since the thread_info was split off
      from the task struct), but that is about to change.
      
      But the patches that move the thread info to be off-stack (and a part of
      the task struct instead) made it clear how confused the allocator and
      freeing functions are.
      
      Because the common case was that we share an allocation with the thread
      stack and the thread_info, the two pointers were identical.  That
      identity then meant that we would have things like
      
      	ti = alloc_thread_info_node(tsk, node);
      	...
      	tsk->stack = ti;
      
      which certainly _worked_ (since stack and thread_info have the same
      value), but is rather confusing: why are we assigning a thread_info to
      the stack? And if we move the thread_info away, the "confusing" code
      just gets to be entirely bogus.
      
      So remove all this confusion, and make it clear that we are doing the
      stack allocation by renaming and clarifying the function names to be
      about the stack.  The fact that the thread_info then shares the
      allocation is an implementation detail, and not really about the
      allocation itself.
      
      This is a pure renaming and type fix: we pass in the same pointer, it's
      just that we clarify what the pointer means.
      
      The ia64 code that actually only has one single allocation (for all of
      task_struct, thread_info and kernel thread stack) now looks a bit odd,
      but since "tsk->stack" is actually not even used there, that oddity
      doesn't matter.  It would be a separate thing to clean that up, I
      intentionally left the ia64 changes as a pure brute-force renaming and
      type change.
      Acked-by: default avatarAndy Lutomirski <luto@amacapital.net>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b235beea
  34. 18 Jun, 2016 1 commit
    • William Breathitt Gray's avatar
      isa: Allow ISA-style drivers on modern systems · 3a495511
      William Breathitt Gray authored
      Several modern devices, such as PC/104 cards, are expected to run on
      modern systems via an ISA bus interface. Since ISA is a legacy interface
      for most modern architectures, ISA support should remain disabled in
      general. Support for ISA-style drivers should be enabled on a per driver
      basis.
      
      To allow ISA-style drivers on modern systems, this patch introduces the
      ISA_BUS_API and ISA_BUS Kconfig options. The ISA bus driver will now
      build conditionally on the ISA_BUS_API Kconfig option, which defaults to
      the legacy ISA Kconfig option. The ISA_BUS Kconfig option allows the
      ISA_BUS_API Kconfig option to be selected on architectures which do not
      enable ISA (e.g. X86_64).
      
      The ISA_BUS Kconfig option is currently only implemented for X86
      architectures. Other architectures may have their own ISA_BUS Kconfig
      options added as required.
      Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
      Signed-off-by: default avatarWilliam Breathitt Gray <vilhelm.gray@gmail.com>
      Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3a495511
  35. 07 Jun, 2016 1 commit